Process for vulcanizing rubber at a low temperature

ABSTRACT

A process for vulcanizing a rubber base comprising at least one halogen-containing amorphous polymer at a low temperature ranging from 5° to 85° C., which comprises carrying out the vulcanization in the presence of 0.01 to 20 parts by weight of an organic hydroperoxide and/or ketone peroxide per 100 parts by weight of the rubber base. 
     In the above process, at least one member selected from the group consisting of (I) the oxides of metals, such as zinc, lead, chromium, cobalt, nickel, magnesium, manganese, copper and iron, or the metallic salts of said metals with aliphatic or cycloaliphatic carboxylic acid having 8 to 24 carbon atoms; (II) methacrylic esters; (III) maleimides; and (IV) oximes, may be used as a vulcanization activator or a vulcanization accelerator in an amount of 0.01 to 20 parts by weight per 100 parts by weight of the rubber base.

This is a division of application Ser. No. 814,918 filed July 12, 1979, now U.S. Pat. No. 4,166,892, which in turn is a continuation of Ser. No. 655,547 filed Feb. 5, 1976, which in turn is a continuation of Ser. No. 429,588 filed Jan. 2, 1974, both now abandoned.

The present invention relates to a process for vulcanizing at least one halogen-containing amorphous polymer at a low temperature. More particularly, it pertains to a process for vulcanizing at least one halogen-containing amorphous polymer at a low temperature, in which an organic hydroperoxide and/or ketone peroxide as a vulcanizing agent is used alone or in combination with a specific vulcanization activator or accelerator to achieve the vulcanization at a temperature as low as from 5° to 85° C.

As the known literature references concerning a low temperature vulcanization process using an organic hydroperoxide as a vulcanizing agent, there are Japanese Patent Publication Nos. 19,930/67 and 16,584/70. These, relate to amorphous copolymers consisting of ethylene, alpha-olefin and cyclic or acyclic polyene having non-conjugated double bond. There is found no literature concerning the halogen-containing amorphous polymers which are the object of the present invention.

At present, halogen-containing amorphous polymers are, in many cases, used in adhesives, paints and sealants. It is greatly significant that a low temperature vulcanization be applicable to these uses. In order to attain this object, therefore, the present inventors have long done extensive research on the low temperature vulcanization of halogen-containing amorphous polymers to achieve this invention. This invention is characterized by using an organic hydroperoxide or ketone peroxide as a vulcanizing agent.

An object of the present invention is to provide a process for vulcanizing halogen-containing amorphous polymers at a low temperature.

Another object of the present invention is to provide a process for vulcanizing at a low temperature halogen-containing amorphous polymers, which process is applicable to adhesives, paints and sealants.

A further object of the present invention is to provide a process for vulcanizing halogen-containing amorphous polymers at a low temperature, in which an organic hydroperoxide or ketone peroxide is used as a vulcanizing agent.

A still further object of the present invention is to provide a process for vulcanizing halogen-containing amorphous polymers at a low temperature, in which an organic hydroperoxide or ketone peroxide as a vulcanizing agent is used together with a vulcanization activator or a vulcanization accelerator.

The other objects and advantages of the present invention will become clear from the following description.

According to the present invention, there is provided a process for vulcanizing a rubber base comprising at least one amorphous polymer at a low temperature ranging from 5° to 85° C., which comprises carrying out the vulcanization in the presence of 0.01 to 20 parts by weight of an organic hydroperoxide and/or ketone peroxide per 100 parts by weight of the rubber base, and, if necessary, in the presence of 0.01 to 20 parts by weight of at least one vulcanization activator or accelerator selected from the group consisting of (I) metal oxides or metallic salts of aliphatic or cycloaliphatic carboxylic acids having 8 to 24 carbon atoms, (II) methacrylates, (III) maleimides and (IV) oximes, per 100 parts by weight of the rubber base.

The halogen-containing amorphous polymers in the present invention include, for example, chloroprene rubber, chlorinated polyethylene, chlorosulfonated polyethylene and chlorinated ethylene-propylene-diene rubber, and the halogens include chlorine and bromine. Chlorine is the most popular and important.

The rubber base in the present invention includes halogen-containing amorphous polymers alone, mixtures thereof and mixtures of halogen-containing amorphous polymer and halogen-free amorphous polymers. More particularly, it includes not only a mixture obtained by mixing the halogen-containing amorphous polymer with the halogen-free amorphous polymer for the purpose of enhancing the weather resistance and heat resistance and reducing the cost of the halogen-containing amorphous polymer but also a mixture obtained by mixing the halogen-free amorphous polymers with the halogen-containing amorphous polymer for the purpose of enhancing the tackiness and adhesiveness of the halogen-free amorphous polymer or imparting flame-proof property to the halogen-free amorphous polymer. In other words, it is indispensible for the rubber base described herein to comprise at least one halogen-containing amorphous polymer. The halogen-free amorphous polymers include, for example, styrene-butadiene rubber, ethylene-propylene-diene rubber and natural rubber. Further, the halogen-free amorphous polymers used for the present invention include low molecular weight amorphous copolymers such as low molecular weight ethylene-propylene rubber, too.

The organic hydroperoxides and ketone peroxides used in the present invention include, for example, alpha-cumyl hydroperoxide, tertiary butyl hydroperoxide, p-menthane hydroperoxide, m,p-diisopropylbenzene-monohydroperoxide, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, acetylacetone peroxide, and the like.

Another great feature of the present invention is that at least one compound belonging to the following groups may be used as a vulcanization activator or a vulcanization accelerator to adjust the vulcanization velocity;

(I) The oxides of metals such as zinc, lead, chromium, cobalt, nickel, magnesium, manganese, copper and iron; and the metallic salts of these metals with aliphatic or cycloaliphatic carboxylic acids having 8 to 24 carbon atoms.

The aliphatic or cycloaliphatic carboxylic acid having 8 to 24 carbon atoms mentioned in group (I) include, for example, n-octoic acid, naphthenic acid, abietic acid, lignoceric acid and 2-ethylhexanoic acid.

(II) Methacrylic esters such as ethylene dimethacrylate, 1,3-butylene dimethacrylate, triethylolpropane trimethacrylate, and the like.

(III) Maleimides such as N,N'-m-phenylene bismaleimide, phenyl maleimide, and the like.

(IV) Oximes such as p-quinone dioxime, p,p'-dibenzoyl quinone dioxime, and the like.

In the present invention the vulcanizing agent is used in an amount of 0.01 to 20 parts by weight, preferably 0.5 to 15 parts by weight per 100 parts by weight of the rubber base. The vulcanization activator or the vulcanization accelerator is used in an amount of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight per 100 parts by weight of the rubber base. The respective quantities of the vulcanizing agent and the vulcanization activator or the vulcanization accelerator are decided depending upon the application and the object. In general, the vulcanization velocity is somewhat accelerated with an increase in amount of these compounding agents. Further, when the vulcanizing agent and the vulcanization activator or accelerator are liquid, they can be applied as they are, or when they are solid, in the form of solutions in proper organic solvents, to the surface of an objective to be vulcanized by spraying or brushing. Accordingly, it is not always necessary to use them in admixture with the rubber base, fillers or other compounding agents.

The rubber base usable for the present invention may contain various fillers such as carbon black, talc, calcium carbonate, etc.; various higher fatty acids; coloring agents; anti-oxidants; ultraviolet absorbers; and softening agents including mineral oils.

By using the process of the present invention, there can be produced various rubber products, sheets, roofings, sealants, adhesives, paints, and the like.

Referring to Examples, the present invention is further illustrated, but should not be interpreted to be limited thereto.

EXAMPLE 1

Using chloroprene rubber as the halogen-containing amorphous polymer, examination was made on the representative vulcanization system with or without vulcanization activator or accelerator. The result thereof is shown below.

Composition

    ______________________________________                                         Chloroprene rubber                                                             (Raw rubber Mooney                                                             viscosity, ML.sub.1+ 4 = 47(100° C.);                                                         100    parts by weight                                   density = 1.23)                                                                SRF carbon black      50     parts by weight                                   Zinc oxide            5      parts by weight                                   Stearic acid          1      parts by weight                                   Naphthenic oil        10     parts by weight                                   Alpha-cumyl hydroper-                                                          oxide (Concentration: 7      parts by weight                                   70% by weight)                                                                 Vulcanization accelerator                                                                            2      parts by weight                                   ______________________________________                                    

Test Method

The above-mentioned materials were blended in a mixing roll and formed into a sheet with a thickness of 1 mm, which was then allowed to stand at 40° C. After a given time, the sheet was subjected to measurement of tensile strength and elongation according to JIS K-6301 (JIS is an abbreviation of Japan Industrial Standards) to examine the vulcanization state. The result obtained is as shown in Table 1.

                                      TABLE 1                                      __________________________________________________________________________            Vulcanization  p-Quinone                                                                               Ethylene                                               accelerator    dioxime  dimethacrylate                                  Vulcanization                                                                         Character-                                                                            T.sub.B                                                                             E.sub.B                                                                           T.sub.B                                                                             E.sub.B                                                                            T.sub.B                                                                             E.sub.B                                    time (day)                                                                            istics (kg/cm.sup.2)                                                                       (%)                                                                               (kg/cm.sup.2)                                                                       (%) (kg/cm.sup.2)                                                                       (%)                                        __________________________________________________________________________     1             27   930                                                                               18   1120                                                                               50   730                                        3             37   700                                                                               46   910 68   450                                        6             36   710                                                                               71   710 77   330                                        __________________________________________________________________________      Note:                                                                          T.sub.B :Tensile strength at break                                             E.sub.B :Elongation at break                                             

EXAMPLE 2

Examination was made on a chlorinated ethylene-propylene-diene rubber as the halogen-containing amorphous polymer. The result thereof is shown below.

Composition

    ______________________________________                                         Chlorinated ethylene-                                                          propylene-diene rubber                                                                          100       parts by weight                                     HAF carbon black 50        "                                                   Zinc oxide       5         "                                                   Stearic acid     1         "                                                   Naphthenic oil   10        "                                                   Alpha-cumyl hydroper-                                                          oxide (Concentration:                                                                           7         "                                                   70% by weight)                                                                 Vulcanization accelerator                                                                       2         "                                                   ______________________________________                                    

The above chlorinated ethylene-propylene-diene rubber was obtained by chlorinating an ethylene-propylene-5-ethylidene-2-norbornene rubber having a raw rubber Mooney viscosity of ML₁₊₄ =40 (100° C.), an iodine value of 12 and a propylene content of 50% by weight, to a chlorine content of 25% by weight.

Test method

The same test method as in Example 1 was repeated. The result obtained is shown in Table 2.

                  Table 2                                                          ______________________________________                                         Vulcanization              p-Quinone                                           accelerator                dioxime                                                          T.sub.B   E.sub.B T.sub.B E.sub.B                                 Characteristics                                                                             2)        (%)     (Kg/cm.sup.2)                                                                          (%)                                     ______________________________________                                         Vulcanization                                                                             1     12        570   12      570                                   time (day)                                                                                5     18        820   24      640                                             10     30        870   45      650                                             20     65        730   135     470                                             30     103       570   165     430                                   ______________________________________                                    

EXAMPLE 3

Using chloroprene rubber, examination was made on metal oxides and metal salts of higher fatty acids as the vulcanization accelerator or activator. The result obtained is shown below.

Composition

The same as in Example 1, except that the amounts of vulcanization accelerator added are as shown in Table 3.

Test method

The same as in Example 1. The result obtained is shown in Table 3.

                                      Table 3                                      __________________________________________________________________________                              Chro-*                                                               Cobalt*                                                                             Iron*                                                                               mium Cobalt*                                                                             Magne-                                                                              Lead       Magne-(*)                   Vulcanization  naphth-                                                                             naph-                                                                               naph-                                                                               abie-                                                                               sium mono-                                                                              Cobalt*(*)                                                                            sium                        accelerator                                                                               --  enate                                                                               thenate                                                                             thenate                                                                             tate oxide                                                                               xide                                                                               abictate                                                                              oxide                       __________________________________________________________________________     Amount (phr)                                                                              --  1    1    1    1    10   10  10     10                          __________________________________________________________________________           Valca-                                                                   Characte-                                                                            niza-                                                                    ristics                                                                              tion                                                                           time                                                                           (day)                                                                          1    27  105  57   44   82   44   32  9      15                          T.sub.B                                                                              3    37  118  72   46   103  81   47  7      21                          (kg/cm.sup.2)                                                                        5    36  100  72   50   101  91   46  8      19                                12   38  102  76   54   110  98   61  11     20                          E.sub.B                                                                              1    930 590  860  880  780  780  850 1110   690                         (%)   3    700 420  630  630  560  580  610 1150   690                               5    700 380  590  600  500  490  580 1000   620                               12   550 340  390  490  400  420  490 1150   680                         __________________________________________________________________________      *Metal content: 5% by weight                                                   (*)Referential Example: alphacumyl hydroperoxide was not mixed.          

Example 3 fully proves the necessity of alphacumyl hydroperoxide as the vulcanizing agent and the effect of the oxides of these metals or the salts of these metals with higher fatty acids as the vulcanization accelerator or activator.

EXAMPLE 4

Examination was made on the effect of a vulcanization accelerator upon chloroprene at 40° C. and 70° C. The result thereof is shown below.

Test method

The same as in Example 1. The result obtained is shown in Table 4.

                                      TABLE 4                                      __________________________________________________________________________                                      Ethylene                                                                             N,N'-m-                                 Vulcanization              p-Quinone                                                                            dimetha-                                                                             phenylene                                                                             Cobalt                           accelerator          --    dioxime                                                                              crylate                                                                              bismaleimide                                                                          abietate                         __________________________________________________________________________              Chloroprene                                                           Compositon                                                                              rubber                                                                (part by weight)                                                                        (Raw Rubber Mooney                                                                          100  100   100   100    100                                       visusity,                                                                      ML.sub.1+4 = 47 (100° C.);                                              Density = 1.23)                                                                SPF carbon black                                                                            50   50    50    50     50                                        Naphthenic oil                                                                              10   10    10    10     10                                        Zinc oxide   5    5     5     5      5                                         Stearic acid 1    1     1     1      1                                         Alpha-cumyl  7    7     7     7      7                                         hydroperoxide                                                                  Vulcanization                                                                  accelerator  0    2     2     2      1                                __________________________________________________________________________     Vulcanization                                                                  temperature (°C.)                                                                            40 70 40 70 40 70 40 70  40 70                            __________________________________________________________________________                      1    38                                                                               105                                                                                50                                                                               111                                                                                66                                                                               102                                                                                76                                                                               118 77 123                           T.sub.B Vulcani- 3    53                                                                               114                                                                                59                                                                               134                                                                                58                                                                               110                                                                                94                                                                               130 106                                                                               128                                   zation   6    55                                                                               102                                                                                56                                                                               141                                                                                55                                                                               108                                                                                98                                                                               144 102                                                                               119                           (kg/cm.sup.2)                                                                          time (day)                                                                              9    56                                                                               106                                                                                61                                                                               136                                                                                61                                                                               --  87                                                                               128 110                                                                               --                                             15   58                                                                               --  69                                                                               --  65                                                                               --  94                                                                               --  108                                                                               --                                             1   880                                                                               380                                                                               870                                                                               320                                                                               520                                                                               270                                                                               560                                                                               160 600                                                                               300                           E.sub.B Vulcani- 3   740                                                                               280                                                                               880                                                                               280                                                                               470                                                                               310                                                                               390                                                                               160 450                                                                               310                           (%)     zation   6   650                                                                               230                                                                               850                                                                               240                                                                               440                                                                               210                                                                               230                                                                               140 430                                                                               250                                   time (day)                                                                              9   680                                                                               220                                                                               810                                                                               240                                                                               400                                                                               -- 290                                                                               130 360                                                                               --                                             15  600                                                                               -- 710                                                                               -- 380                                                                               -- 240                                                                               --  350                                                                               --                            __________________________________________________________________________

EXAMPLE 5

Examination was made on the effect of carbon black upon the low temperature vulcanization of the same chlorinated ethylene-propylene-diene rubber as in Example 2. The result thereof is given below.

Composition

    ______________________________________                                         Chlorinated-ethylene-                                                          propylene-diene rubber                                                                          100     parts by weight                                       Carbon black     50      parts by weight                                       Naphthenic oil   5       parts by weight                                       Zinc oxide       5       parts by weight                                       Stearic acid     1       parts by weight                                       Alpha-cumyl      7       parts by weight                                       hydroperoxide                                                                  p-Quinone dioxime                                                                               2       parts by weight                                       ______________________________________                                    

Test method

The same as in Example 1. The result obtained is shown in Table 5.

                  Table 5                                                          ______________________________________                                         Kind of carbon black                                                                            ISAF    HAF     FEF   GPF                                     ______________________________________                                                           1      13    9     11    8                                   T.sub.B Vulcani-  6      15    14    13    11                                  (kg/cm.sup.2)                                                                          zation    20     123   111   102   68                                          time                                                                           (day)     30     202   149   133   105                                         Vulcani-  1      370   350   390   450                                 E.sub.B zation    6      620   650   790   760                                 (%)     time      20     480   470   520   590                                         (day)     30     330   350   400   450                                 ______________________________________                                    

EXAMPLE 6

Examination was made on mixtures of a halogen-containing amorphous polymer and the halogen-free amorphous copolymer as the rubber base, in which chloroprene rubber was used as the halogen-containing amorphous polymer and the same ethylene-propylene-diene rubber as in Example 2 was used as the halogen-free amorphous copolymer.

Test Method

The same as in Example 1. The result obtained is shown in Table 6.

                                      TABLE 6                                      __________________________________________________________________________            Chloroprene rubber                                                             (Raw rubber Mooney viscosity,                                                                  100 75  50  25  --*                                            ML.sub.1+ 4 = 47 (100° C.);                                             density = 1.23)                                                         Composition                                                                           Ethylene-propylene-diene rubber                                                                --  25  50  75  100                                     (part by                                                                              SRF carbon black                                                                               50  50  50  50  50                                      weight)                                                                               Naphthenic oil  10  10  10  10  10                                             Zinc oxide      5   5   5   5   5                                              Stearic acid    1   1   1   1   1                                              Alpha-cumyl hydroperoxide                                                                      7   7   7   7   7                                              Cobalt abietate 0.5 0.5 0.5 0.5 0.5                                            p-Quinone dioxime                                                                              2   2   2   2   2                                       __________________________________________________________________________                        1   60  47  41  54  87                                      T.sub.B                                                                               Vulcanization                                                                              3   73  64  68  69  101                                     (kg/cm.sup.2)                                                                         time (day)  10  87  88  93  80  102                                                        1   780 660 510 420 340                                     E.sub.B                                                                               Vulcanization                                                                              3   530 490 490 420 350                                     (%)    time (day)  10  400 420 420 340 300                                     __________________________________________________________________________      *: Referential example                                                   

EXAMPLE 7

Examination was made on the effect of vulcanizing agent upon the low temperature vulcanization of chloroprene rubber as the halogen-containing amorphous polymer.

Composition

    ______________________________________                                         Chloroprene rubber                                                             (Raw rubber Mooney viscosity                                                                      100      parts by weight                                    ML.sub.1+ 4 = 47 (100° )                                                density = 1.23)                                                                SRF carbon black   50       parts by weight                                    Naphthenic oil     10       parts by weight                                    Zinc oxide         5        parts by weight                                    Stearic acid       1        parts by weight                                    Cobalt abietate    0.5      parts by weight                                    Vulcanizing agent  1/30     mole.                                              ______________________________________                                    

Test method

The same test method as in Example 1 was repeated, except that vulcanization was carried out at room temperature.

The result obtained is shown in Table 7.

                                      Table 7                                      __________________________________________________________________________                             m,p-Diiso-                                                             Tertiary-                                                                              propyl  p-Menthane                                                                           Methyl ethyl                             Kind of vulca-  butyl   benzene mono-                                                                          hydro-                                                                               ketone                                   nizing agent    peroxide-                                                                              hydroperoxide                                                                          peroxide                                                                             peroxide                                 __________________________________________________________________________                   1 35       69     61    26                                       T.sub.B                                                                              Vulcaniza-                                                                             3 45       93     82    35                                             tion time                                                                              5 53       89     85    45                                       (kg/cm.sup.2)                                                                        (day)   7 72      101     89    48                                                     10                                                                               69      105     94    58                                                     1 830     750     780   810                                      E.sub.B                                                                              Vulcani-                                                                               3 790     700     750   790                                      (%)   zation time                                                                            5 690     690     740   770                                            (day)   7 610     600     700   730                                                    10                                                                               610     50      690   690                                      __________________________________________________________________________ 

What is claimed is:
 1. A process for vulcanizing a non-aqueous rubber base comprising chloroprene rubber, said process comprisingvulcanizing said non-aqueous rubber base at a temperature ranging from 5° to 85° C. in the presence of 0.01 to 20 parts by weight of at least one vulcanizing agent selected from the group consisting of an organic hydroperoxide and ketone peroxide per 100 parts by weight of said rubber, and 0.01 to 20 parts by weight of at least one vulcanization activator or accelerator selected from the group consisting of (1) aliphatic or cycloaliphatic carboxylic acid salts of zinc, lead, chromium, cobalt, nickel, magnesium, manganese, copper, and iron; (2) methacrylates; (3) maleimides; and (4) oximes per 100 parts by weight of said rubber base.
 2. The process of claim 1 wherein said vulcanizing agent is present in an amount of 0.5 to 15 parts by weight.
 3. The process of claim 1 wherein said vulcanizing agent is selected from the group consisting of alpha-cumyl hydroperoxide, tertiary-butyl hydroperoxide, p-menthane hydroperoxide, m,p-diisopropylbenzene monohydroperoxide, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, and acetylacetone peroxide.
 4. The process of claim 1 wherein said vulcanizing agent is alpha-cumyl hydroperoxide.
 5. The process of claim 1 wherein said aliphatic or cycloaliphatic carboxylic acid has 8 to 24 carbon atoms.
 6. The process of claim 1 wherein said vulcanization activator or accelerator is selected from the group consisting of salts of n-octoic, naphthenic, abietic, lignoceric, and 2-ethylhexanoic acids with zinc, lead, chromium, cobalt, nickel, magnesium, manganese, copper, and iron.
 7. The process of claim 1 wherein said vulcanization activator or accelerator is selected from the group consisting of ethylene dimethacrylate, 1,3-butylene dimethacrylate, and triethylolpropane trimethacrylate.
 8. The process of claim 1 wherein said vulcanization activator or accelerator is selected from the group consisting of N,N'-m-phenylene bismaleimide and phenyl maleimide.
 9. The process of claim 1 wherein said vulcanization activator or accelerator is selected from the group consisting of p-quinone dioxime and p,p'-dibenzoyl quinone dioxime. 